The invention relates to a printed circuit board connector.
A typical printed circuit board connector comprises an isolating housing and contact elements which are arranged therein, are preferably formed angled and have a plug-in side, an intermediate portion and a connecting side with contact ends adapted to be mounted at a printed circuit board.
In order to provide a multiple pole plug-in connection, a complementary connector can be plugged into such a printed circuit board connector, the printed circuit board connector being either formed as male connector or female connector. The contact elements arranged in the isolating housing at the plug-in side in rows and columns have contacts which in case of a female connector are formed as spring contacts or in case of a male connector as contact blades and are provided for forming a contact with corresponding contact blades and contact springs, respectively, of the complementary connector.
At the other side of the housing, contact ends connected with the contact elements are provided, the contact ends being adapted to be connected with connecting portions of a printed circuit board. The contact ends are arranged at a right angle with respect to the plug-in direction of the connector.
Typically, the contact ends are soldered to the conductor tracks of the printed circuit board. A problem hereby is that all contact ends at the connecting side need to be heated as uniformly as possible in order to achieve a soldering point at each of the contact ends with an evenly high quality.
German Patent Publication 199 49 160 shows an electrical connector for connecting a conductor track on a printed circuit board, the connector having a housing with a front face and an opposite back face. In the housing are arranged contact chambers in rows and columns, in which angled electrical contacts for contacting a complementary connector accommodated. The contacts have an intermediate portion which is arranged at least partially outside of the housing, and further a solderable connecting portion for contacting and being soldered to a conductor track, the printed circuit board being contacted from two sides.
German Patent 195 17 977 shows an electronical component for being connected to a printed circuit board in a surface mounting technique, conducting elements made from an electrically conducting material being held in an isolating carrier material. The carrier element is provided with at least one window through which energy heating the contact portion can be radiated into the carrier element.
U.S. Pat. No. 5,115,964 shows a solder connection between a flexible circuit carrier and an electronical component. In order to allow to solder the soldering connections of the electronical component to the conductor tracks at the lower side of the circuit carrier, openings are provided in the dielectrical carrier layer of the circuit carrier whereby a heating gas used for soldering is able to heat the conductor tracks and to provide for an electrical connection with the soldering connections arranged below.
It is further known for printed circuit board connectors to have the contact elements completely embedded into an isolating housing with the exception of the protruding contact ends. This leads to high requirements with respect to the position accuracy of the connections to be placed, in particular with connectors which are positioned by means of handling robots on a printed circuit board. The high position accuracy is achieved by forming and mounting the housing of the connector in an exact manner and by using short protruding contact ends in order to prevent any bending of the contact ends. This means that the contact ends are embedded in the isolating housing to the highest possible extent. Accordingly, the contact ends of the contact elements which are for example bent by 90 degrees are mostly embedded in correspondingly shaped housing parts of an isolating housing. This can be achieved by contact elements which are inserted into segments or which are individually embedded and then combined in a carrier housing as a printed circuit board connector.
When components and connectors which are arranged at a printed circuit board are simultaneously soldered in a heating oven in which the energy means for heating a solder paste used as soldering means is a flow of heated air or gas, there is the risk that not all of the soldering ends of the contact elements reach the soldering temperature required for achieving an optimum soldering point simultaneously, that is at the same time with other components of the printed circuit board, this being due to the encapsulated and thereby thermally isolating construction of such printed circuit board connectors. In case of an excessive sejourn time in the heating oven, this can lead to an excessive temperature and to destruction of the electronical components, and an insufficient sejourn time can result in defective soldering points.
The invention is based on the object of improving a printed circuit board connector of the type initially mentioned so that all soldering ends of the contact elements are uniformly and without delay sufficiently exposed to a heating energy in order to allow for being soldered to a printed circuit board.
The invention provides a printed circuit board connector having an isolating housing, contact elements arranged in the housing, each the said contact elements comprising a plug-in side, an intermediate portion and a connecting side with contact ends adapted to be mounted at a printed circuit board, and having a plurality of channels which are in touch with the intermediate portions of the contact elements. The advantages provided by the invention particularly reside in the fact that the channel allows the heating gas to flow through the interior of the connector even when a large number of contact elements are arranged in rows in a staggered manner, the flow of heated gas allowing to quickly heat the internally arranged intermediate portions of the contact elements. Due to the good thermal conductivity of the contact elements made from metal, this allows to quickly heat the contact ends which leads to a uniform soldering.
The intermediate portions of the contact elements may project into the channel or be formed adjacent thereto. In any case, it is important to achieve a good heat transfer from the medium flowing through the channel to the intermediate portions.
According to a preferred embodiment of the invention, the channel is formed from a first partial channel extending approximately perpendicularly with respect to the printed circuit board, and a second partial channel extending approximately parallel to the printed circuit board. The first partial channel can be formed by a recess extending approximately perpendicularly with respect to the printed circuit board, the recess being formed in segments which accommodate the contact elements. The second partial channel can be formed by a distance between the surface of the printed circuit board and intermediate walls of a segment holder which holds the segments accommodating the contact elements. The distance between the intermediate walls of the segment holder and the surface of the printed circuit board may change over the intermediate wall. Using two partial channels which are perpendicularly with respect to each other allows to use a printed circuit board without an opening which is aligned with the channel extending perpendicularly with respect to the printed circuit board. Accordingly, the printed circuit board need not be adapted to the connector, which is an advantage. The partial channel extending perpendicularly with respect to the printed circuit board assists in the circulation of the hot gases through the channel by acting in the manner of a chimney.
According to the preferred embodiment, a second channel extending approximately perpendicularly with respect to the printed circuit board is provided at the plug-in portion of the contact elements in the isolating housing. This allows to heat the contact elements arranged in the inner centre.
An additional advantage results from suitably formed contact ends of the contact elements which allows to use contact elements with press-in contact ends in an otherwise unchanged housing. This is advantageous since the angled printed circuit board connector intended for being soldered in surface mounting technique can be pressed into bores in a printed circuit board with a simple, flat tool.
Advantageous details of the invention are specified in the subclaims.